1. Field of the Invention
The present invention relates to a nozzle plate and a method of manufacturing a nozzle plate, and more particularly, to a method of manufacturing a nozzle plate in which a liquid-repelling film is formed on the surface thereof on the droplet ejection side.
2. Description of the Related Art
An inkjet type of image forming apparatus comprises a print head having a nozzle plate in which a plurality of nozzles (nozzle holes) are formed, and the image forming apparatus forms an image on a recording medium by ejecting ink droplets from these nozzles.
In order to stabilize the direction of flight of the ink droplets ejected from the nozzles, a liquid-repelling film is conventionally formed on the surface of the nozzle plate on the droplet ejection side. This is because, if there are ink droplets attached to the surface of the nozzle plate on the ink droplet ejection side (and in particular, in the periphery of the nozzles), then they can affect the direction of flight of the ink droplets ejected from the nozzles. By forming the liquid-repelling film, the ink droplets adhering to the surface of the nozzle plate on the ink droplet ejection side can be removed more readily by means of a blade or the like.
As a method of manufacturing a nozzle plate of this kind, Japanese Patent Application Publication No. 9-76492, for example, discloses a method in which a dry film resist made of a corrosion-resistant high polymer resin, such as a photosensitive film, or the like, is filled into the nozzles, the dry film is made to project by cutting by etching, and a surface treatment layer is then formed, whereupon the dry film is removed.
However, in the method in which the resist is filled into the nozzles, there is a problem in that the number of manufacturing steps for the nozzle plate increases and the work becomes more complicated. In particular, if the nozzle plate is large in size or complicated in shape, then the process of manufacturing the nozzle plate becomes more complicated and this leads to an increased number of manufacturing steps.
Furthermore, Japanese Patent Application Publication No. 2004-181883 discloses a method in which a liquid-repelling treatment liquid is applied onto the ink ejection surface of the nozzle plate by spin-coating, while introducing air into the nozzle holes from the other side of the nozzle plate reverse to the ink ejection surface, whereupon the nozzle plate is heat treated.
However, in the method in which the liquid-repelling treatment liquid is applied while introducing air into the nozzle holes, it is difficult to apply a highly viscous treatment liquid, and to form a thick film of the treatment liquid, due to the effects of the air flow, and therefore it is difficult to form a secure liquid-repelling film on the surface of the nozzle plate. Furthermore, if the nozzle plate is large in size, or is made to contain a large number of nozzles, then it is difficult to control the air pressure, due to the deformation of the nozzle plate as a result of the air pressure.